March 30, 2011

Do the Wave!

The electromagnetic spectrum represents the many types of radiation as a group. Radiation occurs when energy is released and travels in moving particles or waves. Electromagnetic waves are transverse waves that have amplitude, velocity, wavelength and frequency. In addition, these waves do not need a medium to travel through - they are able to travel by vacuum! These are the seven type of radiation, listed from lowest frequency and longest wavelength to highest frequency and shortest wavelength: radio, microwaves, infrared, visible, ultraviolet, X-rays and gamma rays. I am going to discuss two of these types of radiated waves in depth: radio waves and X-rays.

Radio waves have two main characteristics, directness and noise occurrence. The "directness" of a wave is how straightforward the wave is in reaching its target. A radio wave's directness depends on the frequency of the waves; if the frequency is higher, the radio waves' wavelength decreases and their directness increases. The "noise occurrence" of a radio wave is the occurrence of a noise produced when the radio wave has been interrupted by a medium. The delay between waves, which is caused by this medium, results in a static noise. The noise occurrence of a radio wave is present when the radio waves are weak, and the further the receiver is from the base which is emitting these waves, the weaker the waves are. The frequency of a radio wave varies from 3 kHz to 300 GHz, and their average wavelength is 1.5 x 10^3 meters. In the real world, radio waves are most frequently used for radio communication. For example, many people have radios either in their households or in their cars which are built to receive radio waves emitted by a antennae (shown in the picture above) from a single, non-portable base unit such as a radio station. These stations play music that then travels to the antennae of the portable radios.

X-rays are recognized by their velocity, wavelength, amplitude and frequency. The velocity of an x-ray in a vacuum is 186,000 miles/second, and its velocity is less when travelling through transparent matter. The wavelength of an x-ray is very short - an average of 10^-8 meters! An x-ray has amplitude equal to its intensity, and a frequency equal to its velocity divided by its wavelength. X-rays are commonly used in the real world for doctoring purposes. Doctors can take images of their patient's bones by using a special camera and film which capture images of trapped x-rays. This works perfectly for taking pictures of human bone because although x-rays can pass easily through soft human tissue, but have trouble passing through a hard material like bone.

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  1. great posting! I liked how you described each of the two waves in depth and gave thorough examples about how each are used. I would consider revising the sentence in your first paragraph when you talk about how the waves are ordered...they aren't arranged by energy, but by wavelength and frequency. Also, you might want to mention the fact that waves do not need a medium to travel through because they are able to travel by vacuum. Overall, it is a very solid posting that explains the electromagnetic spectrum well.

  2. Thanks Erika!
    I have made the changes you've suggested, and I appreciate your compliments on my blog posting.

  3. Great posting overall.
    Please add a little explanation under your second image as I do not know what it represents.
    In the radio waves section you mentioned two terms that we did not discuss in class therefore you need to explain what they mean: "directness and noise occurrence". What are they, how are they measured, How are they related to modulation etc. The section is too technical which is not a bad thing but needs to be clear to your audience.

  4. Mrs. Gende, thank you for the suggestions! I made the changes you advised me to make. Also, hank you for notifying me about the technicality of my radio section. I edited it so that it is easier for the reader to understand. Thanks again!